The English word “effeminate” harkens back to a time in history when “femininity” occupied the lowest rung of the social ladder. We get the word “virtue” from the Latin word “virtus,” which itself came from “vir,” meaning man. Think about that. Historically, virtue was inherently masculine. The implication for the feminine isn’t that difficult to figure out.
Even today, we stumble under the weight of our misogynistic history, commonly associating the feminine with what is "less." People still say things like, “You throw like a girl,” and hardly think twice about the implications. What’s more, people still write articles condemning men who don’t fit a very narrow construction of masculinity by accusing them of being womanly, or “effeminate.”
Most recently, Desiring God published two articles touching upon the topic of effeminacy (linked above), where gay men are condemned for their "effeminate habits," first implicitly and then explicitly. But the most common passages of Scripture used to justify this sort of thinking paint a very different picture of what effeminacy actually entails.